Documentation
1. Purpose
Implement the queue Data sructure using stack data sructure
which supports the basics operation like queuee , dequeue cheking the
size of queue , finding the first element od queue without removing.
2. Solution and algorithm
Algortihm are very identical to stack supports like pushing and popping
for solution please refer the code, used two stacks for achieving the goal
both stack are internal class in java library
3 . Data structure
1. Qeueu
2. Stack
4. How to run program
Program is menu driven where you will get prompted to input or can say you need to
select the option showing on the screen . Simply Run the MyQueue class in which main methos is implemented.
Programming:
All requirement in MyQueue class itself
Please find below the required code
save the below code as MyQueue.java
import java.util.NoSuchElementException;
import java.util.Scanner;
import java.util.Stack;
/**
* This is generic Queue implementation using two stacks
* that can be used with any data type
* it supports queue operations like
* enqueue dequeue
* and have some utility methods
* isEmpty, peek
* @author YourName
*
* @param <T>
*/
public class MyQueue<T> {
//two stack used for
//one for pushing and one for pop the element
private Stack<T> s1;
private Stack<T> s2;
//constructor MyQueue that initialize both stacks
public MyQueue() {
s1 = new Stack<T>();
s2 = new Stack<T>();
}
/**
* this method is used for checking the queue
* if no element return true
* @return if no element return true else false
*/
public boolean isEmpty() {
return s1.isEmpty() && s2.isEmpty();
}
/**
* used this method to check size of queue
* @return summed of both stacks sizes s
*/
public int size() {
return s1.size() + s2.size();
}
/**
* this method for demonstating the
* first element in queue
* @return first element in queue
*/
public T peek() {
if (isEmpty()) throw new NoSuchElementException(“Queue underflow”);
if (s2.isEmpty()) moveTemp();
return s2.peek();
}
/**
* this method is used to move element from
* s1 to s2 for dequeue
*/
private void moveTemp() {
while (!s1.isEmpty())
s2.push(s1.pop());
}
/**
* this method for used to enqueue element
* in the queue
* @param item
*/
public void enqueue(T item) {
s1.push(item);
}
/**
* this method is used to remove element from queue
* @return dequeued element or first element in queue
*/
public T dequeue() {
if (isEmpty()) throw new NoSuchElementException(“Queue underflow”);
if (s2.isEmpty()) moveTemp();
return s2.pop();
}
/**
* main method for demonstrating the MyQueue
* class
* @param args
*/
public static void main(String[] args) {
//created queue for string data type
MyQueue<String> q = new MyQueue<String>();
int userChoice;
Scanner sc = new Scanner(System.in);
//menu driven program for MyQueue
while(true)
{
System.out.println(“1.Enqueue the elements”);
System.out.println(“2.Dequeue the elements”);
System.out.println(“3.Check the MyQueue Size”);
System.out.println(“4.Check if MyQueue is empty”);
System.out.println(“5.See the first element in MyQueue”);
System.out.println(“6.Exit”);
System.out.print(“Enter the choice : “);
userChoice=sc.nextInt();
switch(userChoice){
case 1:System.out.print(“Enter the element to enqueue : “);
String temp = sc.next();
q.enqueue(temp);
break;
case 2:System.out.println(“Dequed Element : “+q.dequeue());
break;
case 3:System.out.println(“Size of MyQueue : “+q.size());
break;
case 4:System.out.println(“IS MyQueue Empty ? :”+q.isEmpty());
break;
case 5:System.out.println(“First element in queue : “+q.peek());
break;
case 6:System.exit(0);
default : System.out.println(“Invalid entry , please try again !”);break;
}
}
}
}//end of class
//OUTPUT
p
